shill: LinkMonitor: Fixup local/remote order

ARP responses will have the "local" fields of the ARP
header populated with the "remote" addresses, from the
perspective of the recipient.  Fix this misunderstanding.

BUG=chromium-os:32600
TEST=Manual -- ran on real system (after following CLs)

Change-Id: I0e34fdada9b0f1b149d0569cf1d942ca67466ea5
Reviewed-on: https://gerrit.chromium.org/gerrit/29793
Commit-Ready: Paul Stewart <pstew@chromium.org>
Reviewed-by: Paul Stewart <pstew@chromium.org>
Tested-by: Paul Stewart <pstew@chromium.org>
diff --git a/mock_link_monitor.h b/mock_link_monitor.h
index 083b5d2..b76137d 100644
--- a/mock_link_monitor.h
+++ b/mock_link_monitor.h
@@ -18,7 +18,8 @@
 
   MOCK_METHOD0(Start, bool());
   MOCK_METHOD0(Stop, void());
-  MOCK_METHOD0(GetResponseTimeMilliseconds, unsigned int());
+  MOCK_CONST_METHOD0(GetResponseTimeMilliseconds, unsigned int());
+  MOCK_CONST_METHOD0(IsGatewayFound, bool());
 
   DISALLOW_COPY_AND_ASSIGN(MockLinkMonitor);
 };